Accessory Dwelling Units (ADUs)

An accessory dwelling unit (ADU), also referred to as a second unit or in-law unit, is a dwelling unit that provides complete, independent living facilities on the same lot as a single-family or multi-family dwelling. Independent living facilities includes permanent provisions for living, sleeping, eating, cooking and sanitation (restroom/wash facilities). ADUs can be attached or detached from the main dwelling unit(s) on-site. Additionally, an ADU of 500 square feet or less in size with an efficiency kitchen, with or without sanitation facilities, is called a junior accessory dwelling unit (JADU) and is permitted within a single-family home. 

The approval process for ADUs and JADUs is ministerial, which means that only a building permit and any related permits are required. No planning permit with public notice or public hearing is required. The City encourages all applicants to thoroughly review the City’s ADU/JADU regulations to ensure the project meets all zoning requirements prior to preparing detailed construction plans for building permit submittal.

ADU Regulations and Process Resources

• Los Altos ADU Information Guide
• Los Altos City Code: ADU/JADU Regulations
• Building Permit Submittal Requirements

Additional Resources

The City of Los Altos has partnered with other Santa Clara County cities to create a centralized resource for property owners interested in constructing an ADU on their property. Santa Clara County ADU provides resources to help residents through the entire process of building an ADU and includes information on cost, regulations, permits, design plans, rent and more.

Permit-Ready ADU Program

To implement Program 2.D of the City’s adopted 2023 Housing Element and encourage the construction of ADUs as a form of affordable housing, Development Services staff is working with an architectural consulting firm to develop construction drawings for three different detached ADU plans in three different architectural styles.

The schematic plans currently include a studio/one-bedroom, a one-bedroom, and a two-bedroom ADU ranging in size from 500 to 1200 square feet. Each of the three ADU plans will be available in three architectural styles (Mediterranean, Contemporary, and Traditional) for compatibility with the primary dwelling.

The permit-ready ADU plans will enable property owners to reduce the cost and time associated with constructing ADUs by eliminating the need for design/engineering services and simplifying the permit process. The permit-ready ADU plans will be available free of charge and will include structural plans and calculations, mechanical, electrical, and plumbing plans, and energy code reports.

Following a February 21, 2024 community meeting to collect feedback on the schematic plans, construction drawings are currently being developed and the process is expected to take several months. 

Please continue to check the website for updates.

Contact

For questions regarding the Permit-Ready ADU Program, please contact Naz Healy at nhealy@losaltosca.gov or (650) 947-2640.